Practice Questions

Q17.A single slit of width a is illuminated by a monochromatic light of wavelength 600 nm . The value of a for which first minimum appears at θ = 30o on the screen will be : (1) 1. 2 μm (2) 3 μm (3) 1. 8 μm (4) 0. 6 μm

Q17.A cell of emf 90 V is connected across series combination of two resistors each of 100 Ω resistance. A voltmeter of resistance 400 Ω is used to measure the potential difference across each resistor. The reading of the voltmeter will be: (1) 40 V (2) 45 V (3) 80 V (4) 90 V

Q18.The angular momentum for the electron in Bohr’s orbit is 𝐿. If the electron is assumed to revolve in second orbit of hydrogen atom, then the change in angular momentum will be (1) Zero (2) 2𝐿 (3) 𝐿 (4) 𝐿 2

Q18.The de Broglie wavelength of an electron having kinetic energy E is λ . If the kinetic energy of electron becomes E , then its de-Broglie wavelength will be: 4 (1) √2λ (2) λ √2 (3) λ (4) 2λ 2

Q18.Speed of an electron in Bohr’s 7th orbit for Hydrogen atom is 3 . 6 × 106 m s-1. The corresponding speed of the electron in 3rd orbit, in m s-1 is : (1) 1 . 8 × 106 (2) 7 . 5 × 106 (3) 3 . 6 × 106 (4) 8 . 4 × 106

Q18.The number density of free electrons in copper is nearly 8 × 1028 m−3 . A copper wire has its area of cross- section = 2 × 10−6 m2 and is carrying a current of 3. 2 A . The drift speed of the electrons is _____ ×10−6 m s−1 .

Q18.The H amount of thermal energy is developed by a resistor in 10 s when a current of 4 A is passed through it. If the current is increased to 16 A , the thermal energy developed by the resistor in 10 s will be (1) H (2) 16H (3) H (4) 4H 4

Q19.The output from a NAND gate having inputs A and B given below will be, (1) (2) (3) (4)

Q19.A massage signal of frequency 3 kHz is used to modulate a carrier signal of frequency 1 . 5 MHz. The bandwidth of the amplitude modulated wave is (1) 6 MHz (2) 6 kHz (3) 3 MHz (4) 3 kHz

Q19.The resistivity ( 𝜌) of semiconductor varies with temperature. Which of the following curve represents the correct behaviour? (1) (2) (3) (4)

Q19.The logic performed by the circuit shown in figure is equivalent to JEE Main 2023 (11 Apr Shift 1) JEE Main Previous Year Paper (1) AND (2) NOR (3) OR (4) NAND

Q19.The effect of increase in temperature on the number of electrons in conduction band ( 𝑛𝑒) and resistance of a semiconductor will be as: JEE Main 2023 (31 Jan Shift 1) JEE Main Previous Year Paper (1) Both 𝑛𝑒 and resistance decrease (2) Both 𝑛𝑒 and resistance increase (3) 𝑛𝑒 increases, resistance decreases (4) 𝑛𝑒 decreases, resistance increases

Q20.A single turn current loop in the shape of a right angle triangle with sides 5 cm, 12 cm, 13 cm is carrying a current of 2 A . The loop is in a uniform magnetic field of magnitude 0. 75 T whose direction is parallel to the current in the 13 cm side of the loop. The magnitude of the magnetic force on the 5 cm side will be 130x N . The value of x is _______.

Q20.To radiate EM signal of wavelength 𝜆 with high efficiency, the antennas should have a minimum size equal to: (1) 2𝜆 (2) 𝜆 2 (3) 𝜆 (4) 𝜆 4

Q20.A solenoid of 1200 turns is wound uniformly in a single layer on a glass tube 2 m long and 0. 2 m in diameter. The magnetic intensity at the center of the solenoid when a current of 2 A flows through it is: (1) 2. 4 × 103 A m−1 (2) 1. 2 × 103 A m−1 (3) 1 A m−1 (4) 2. 4 × 10−3 A m−1

Q20.The amplitude of 15sin ( 1000π𝑡) is modulated by 10sin ( 4π𝑡) signal. The amplitude modulated signal contains frequency (ies) of ( 𝐴) 500 Hz ( 𝐵) 2 Hz ( 𝐶) 250 Hz ( 𝐷) 498 Hz ( 𝐸) 502 Hz Choose the correct answer from the options given below: (1) A only (2) A, D and E only (3) B only (4) A and B only

Q20.A coil is placed in magnetic field such that plane of coil is perpendicular to the direction of magnetic field. The magnetic flux through a coil can be changed: A. By changing the magnitude of the magnetic field within the coil. B. By changing the area of coil within the magnetic field. C. By changing the angle between the direction of magnetic field and the plane of the coil. D. By reversing the magnetic field direction abruptly without changing its magnitude. Choose the most appropriate answer from the options given below: (1) A and B only (2) A, B and C only (3) A, B and D only (4) A and C only

Q20.A current carrying rectangular loop PQRS is made of uniform wire. The length PR = QS = 5 cm and PQ = RS = 100 cm. If ammeter current reading changes from I to 2I , the ratio of : f PQ)2I is: magnetic forces per unit length on the wire PQ due to wire RS in the two cases respectively (f PQI JEE Main 2023 (30 Jan Shift 2) JEE Main Previous Year Paper (1) 1 : 2 (2) 1 : 4 (3) 1 : 5 (4) 1 : 3

Q20.A carrier wave of amplitude 15 V is modulated by a sinusoidal base band signal of amplitude 3 V. The ratio of maximum amplitude to minimum amplitude in an amplitude modulated wave is 3 (1) 2 (2) 2 (3) 1 (4) 5

Q20.A compass needle oscillates 20 times per minute at a place where the dip is 30o and 30 times per minute where the dip is 60o . The ratio of total magnetic field due to the earth at two places respectively is 4 . The value of √x x is

Q21.The length of a metallic wire is increased by 20% and its area of cross-section is reduced by 4 % . The percentage change in resistance of the metallic wire is ________ .

Q21.An electron is allowed to move with constant velocity along the axis of current carrying straight solenoid. (A) The electron will experience magnetic force along the axis of the solenoid. (B) The electron will not experience magnetic force. (C) The electron will continue to move along the axis of the solenoid. (D) The electron will be accelerated along the axis of the solenoid. (E) The electron will follow parabolic path-inside the solenoid. Choose the correct answer from the option given below: (1) B, C and D only (2) A and D only (3) B and C only (4) B and E only

Q21.A car accelerates from rest of 𝑢 m s-1. The energy spent in this process is 𝐸 J. The energy required to accelerate the car from 𝑢 m s-1 to 2𝑢 m s-1 is 𝑛𝐸 J. The value of 𝑛 is _____. JEE Main 2023 (13 Apr Shift 2) JEE Main Previous Year Paper

Q21.A block of mass 10 kg is moving along x-axis under the action of force F = 5x N . The work done by the force in moving the block from x = 2 m to 4 m will be _______ J.

Q21.Vectors 𝑎 ^𝑖+ 𝑏 ^𝑗+ ^𝑘 and 2 ^𝑖- 3 ^𝑗+ 4 ^𝑘 are perpendicular to each other when 3𝑎+ 2𝑏= 7, the ratio of 𝑎 to 𝑏 is 𝑥 2. The value of 𝑥 is _____.